Levels Of OrganizationLevels Of Organization

7.3.1 Summarize the levels of 7.3.1 Summarize the levels of organization within the human organization within the human body (including cells, tissues, body (including cells, tissues,

organs, and systems).organs, and systems).

The levels of organization from The levels of organization from simplest to most complex are:simplest to most complex are:

CellsCells Tissues Tissues OrgansOrgans SystemSystem OrganismOrganism

CellsCells The basic unit of structure and The basic unit of structure and

function in the human bodyfunction in the human body Though all cells perform the processes Though all cells perform the processes

that keep humans alive, they also that keep humans alive, they also have specialized functions as well.have specialized functions as well.

Examples may be nerve cells Examples may be nerve cells (neurons), blood cells, and bone cells.(neurons), blood cells, and bone cells.

TissuesTissues

A group of specialized cells A group of specialized cells that work together to perform that work together to perform the same function.the same function.

There are four basic types of There are four basic types of tissue in the human body:tissue in the human body:

TissuesTissues1.1. Nerve tissueNerve tissue – carries – carries

impulses back and forth to impulses back and forth to the brain from the bodythe brain from the body

Three types of muscle tissueThree types of muscle tissue Muscle tissueMuscle tissue – (cardiac, smooth, skeletal) – (cardiac, smooth, skeletal)

contract and shorten, making body parts movecontract and shorten, making body parts move Skeletal Skeletal

CardiacCardiac

SmoothSmooth

3. Epithelial tissue – covers the surfaces of 3. Epithelial tissue – covers the surfaces of the body, inside (as lining and /or covering the body, inside (as lining and /or covering of internal organs) and outside (as layer of of internal organs) and outside (as layer of skin)skin)

4. Connective tissue – connects all parts of 4. Connective tissue – connects all parts of the body and provides support (for the body and provides support (for example tendons, ligaments, cartilage).example tendons, ligaments, cartilage).

OrgansOrgans A group of two or more different types A group of two or more different types

of tissue that work together to perform of tissue that work together to perform a specific function.a specific function.

The task is generally more complex The task is generally more complex than that of the tissue.than that of the tissue.

For example, the heart is made of For example, the heart is made of muscle and connective tissues which muscle and connective tissues which functions to pump blood throughout functions to pump blood throughout the body.the body.

SystemsSystems A group of two or more organs that work A group of two or more organs that work

together to perform a specific function. together to perform a specific function. Each organ system has its own function but Each organ system has its own function but

the systems work together and depend on the systems work together and depend on one another. one another.

There are eleven different organ systems in There are eleven different organ systems in the human body: circulatory, digestive, the human body: circulatory, digestive, endocrine, excretory (urinary), immune, endocrine, excretory (urinary), immune, integumentary, muscular, nervous, integumentary, muscular, nervous, reproductive, respiratory, and skeletal.reproductive, respiratory, and skeletal.